1. Field of The Invention
The present invention relates to a linear guide device for use in moving a head in a magneto-optical disk recording/regenerating device, a floppy disk drive FDD) and the like.
2. Discussion of Related Art
The following device as shown in FIGS. 16 to 18 is known as a linear guide device for use in moving a head in a magneto-optical disk recording/regenerating device, a floppy disk drive (FDD) and the like.
A motor 2 on which a disk-shaped recording medium D is placed and which engages an output shaft and rotates the recording medium D is disposed on a chassis 1. The chassis 1 is provided with a head traveling space 4 whose upper side is open. A pair of head guide members 5 arranged parallel to each other are provided between two ends of the head traveling space 4. The head guide members 5 are slidably fitted with a head 3. The head 3 is slidably guided substantially linearly along the head guide members 5.
Each of the head guide members 5 is shaped into a cylindrical form and is fitted in a metal bearing 3a provided in the head 3 to thereby slidably support the head 3. Referring to FIG. 18, each of both ends of each head guide member 5 is supported on a support step part 1a formed on the chassis 1 and is fixed in the state of being pressed against one side wall of the step part 1a by means of a leaf spring 7 secured to a bottom wall of the step part 1a by means of a screw 6.
However, the device of the above structure has the following problem.
That is, referring to FIGS. 16 and 18, an objective lens 8 for focusing laser beams on a given position of the recording medium D is disposed on an upper part of the head 3. This objective lens 8 is driven in the arrowed X- and Z-directions respectively parallel and perpendicular to the recording medium D by means of a voice coil, etc. when the recording medium D is rotated by means of the motor 2. The follow-up action of the objective lens 8 to the recording medium D is conducted up to a frequency as relatively high as 3 to 4 kHz, so that the objective lens 8 is generally vibrated at a high frequency.
However, the vibration reaction force of this objective lens 8 is conveyed via the head 3 to the head guide member 5 and further conveyed via the chassis 1 and the motor 2 to the recording medium D. The head guide member 5, chassis 1 and motor :2 are mainly composed of respective metal members, so that the vibration is conveyed with especially high accuracy. When the recording medium D is thus vibrated, the objective lens 8 tries to follow up the vibration of the recording medium D because of the need of focusing itself. What is known as the state of positive feedback is reached. At that time, the problem has been experienced that, for example, the additional disturbance of the natural frequencies of the recording medium D, motor 2 and head guide member 5 leads to immediate occurrence of an oscillating condition with the result that the control of the objective lens 8 is lost to thereby disenable the follow-up action to the recording medium D.
The following invention for solving the above problem was proposed in, for example, Japanese Patent Application Laid-Open Specification No. 281223/1992.
In the above invention, referring to FIG. 19, a rodlike head guide member 5 supporting a recording/regenerating head in a fashion enabling substantially linear movement of the recording/regenerating head is disposed on a chassis 1. A coupling part 10 is bonded to an end of a principal part 9 of the head guide member 5. A connecting part 10b is connected to the coupling part 10. A locking edge 10c secured to the chassis 1 by means of a screw 6 is connected to the connecting part 10b.
This connecting part 10b is formed from a thin plate resin or hard rubber or a metal plate spring and is characterized in that the natural frequency of the connecting part 10b along at least one direction there-of is lower than any of those of the above coupling part 10, principal part 9 and locking edge 10c.
In the device of the above structure, the vibration of the recording/regenerating head at the driving of a recording medium because of the follow-up action to the recording medium is accompanied by the conveyance of the vibration reaction force of the head to the principal part 9 of the head guide member 5. This vibration is effectively damped by the connecting part 10b whose natural frequency is low. Therefore, either the vibration is not conveyed to the recording medium at all or the conveyed vibration is negligible so that the occurrence of an oscillating condition can be suppressed.
However, the invention of Japanese Patent Application Laid-Open Specification No. 281223/1992 has the following drawbacks.
That is, each of both ends of the principal part 9 of the guide member is supported by, for example, the connecting part 10b which is composed of another material of low rigidity. Therefore, the construction of the locking part for the guide member is complex, so that the cost is increased.
Further, the low rigidity of the member fixing at each of both ends of the guide member causes instability. In the application of a vibrating force to the guide member by, for example, outside vibration or the moving of the recording/regenerating head, even if the vibrating force is very minute, the guide member is vibrated, so that the recording/regenerating head is shifted or leaned, thereby disenabling attainment of desirable servo and recording/regenerating characteristics.